How to turn a tanker into a sailboat

Sails on tanker ships could help the shipping industry cut fuel costs and reduce its impact on the environment, according to a German sail-making company.

Hamburg-based SkySails claims that its system, which is already in use on two ships, can cut fuel consumption by up to 50 per cent, reducing costs as well as emissions of carbon dioxide and sulphur.

SkySails founder Stephan Wrage came up with the idea of propelling ships with a towing kite at the tender age of 15.

The kit consists of a large parachute-like kite, a mechanism for launch and recovery, and a system that controls the sail remotely from the ship's bridge.

The SkySail takes takes between 10 and 20 minutes to deploy, the company says, and will work in wind speeds ranging from about 8 to 45mph. Launching it in bad weather is difficult, but engineers are working on a system that would help to compensate for tricky weather conditions.

Their research found that a 160 square metre kite generates up to eight metric tonnes of pulling power, which is roughly equivalent to the thrust of an Airbus A318 turbine engine. It's also about five times more power per square metre of sail area than conventional ships' sails.

Gerd Wessels, managing director of the Wessels shipping company said that the SkySail system had made his ship go faster. "We were able to increase the ship’s cruising speed from 10 to 11.6 knots with the help of towing kite propulsion," he said.

For shipping companies, this means fuel and therefore cost savings. SkySail says that a ship will burn between 10 and 35 per cent less fuel over the course of a year, which they say adds up to an average annual saving of more than £270,000 for a 160m long tanker.

The shipping industry is also being forced to look at oil consumption in environmental terms. In April 2008, the International Maritime Organisation agreed to introduce a reduction in sulphur emissions for the shipping industry, which comes into force from 2020. It is also working on regulations that would cut carbon emissions.

Wessels acknowledges that meeting the standards and cutting fuel costs are primary concerns for ship owners, and says that he will order SkySail systems for his next three ships.

SkySails has set itself the ambitious goal of equipping 1,500 ships with its system by the year 2015. It says that if 60,000 of the 100,000 ships worldwide could be fitted with sails – admittedly, an unlikely target – 150 million tonnes of carbon dioxide emissions could be saved every year.